@Rtez and @MAS-76 - I have done extensive testing on the two com.apple.windowserver.plist files - the one in /Library/Preferences/ and the other in your user's preferences location (/Users/yourusername/Library/Preferences/ByHost/) - in the past, but neither help alleviate strain on either Intel or M1/M2 macOS devices.
In the plist file, setting each of the "Depth" and "DepthFormat" keys to a value of "4" is essentially what SwitchResX does when you toggle the 'Millions of colors' (vs 'Billions of colors') display option in the application. And as you make these changes in the com.apple.windowserver.plist file against a specific "DisplayID", it can be made to apply not only to an external monitor but also the internal display. -A small excerpt of the file from one of my computers with the bit depth reduced:
<dict>
<key>Active</key>
<integer>1</integer>
<key>Depth</key>
<integer>4</integer>
<key>DisplayID</key>
<integer>69495695</integer>
...
<key>Mode</key>
<dict>
<key>BitsPerPixel</key>
<integer>32</integer>
<key>BitsPerSample</key>
<integer>8</integer>
<key>DepthFormat</key>
<integer>4</integer>
<key>Height</key>
<integer>1200</integer>
...I've done my testing on a range of 2013 and 2014 Macs (which were once good, but have now all gone bad on me). As well as 2016 and 2020 Intel MacBooks. Along with a variety of 2021 and 2022 M1 and M2 MacBooks. And have spent countless hours analyzing Apple source code in hopes of finding some new property key which I could exploit through these plists, but so far I have not found any combination that truly alleviates the strain through these plists.
For anyone who does want to tweak these plists - rather than going the convoluted plutil process detailed in that video, I would highly recommend downloading a text editor like BBEdit which allows you to directly modify and save the XML file.